Conventionally, various reactions for epoxidizing olefins using a tungsten compound and hydrogen peroxide as oxidizing agents together with a co-catalyst have been known. For example, Patent document 1: JP-A-8-27136 describes a process for epoxidation using α-aminomethylphosphonic acid and a phase-transfer catalyst.
Further, Patent document 2: JP-A-2003-192679 and Patent document 3: JP-A-2003-192680 describe a process for epoxidizing olefins by adding hydrogen peroxide to a two-phase solution composed of an organic phase containing an olefin compound and a quaternary ammonium salt and an aqueous phase containing a tungsten compound and phosphoric acid or the like.
However, since none of these processes can provide a sufficient catalytic activity for some substrates to be oxidized, and in the former process, α-aminomethylphosphonic acid as an essential component is expensive, etc., development of a novel oxidation catalyst being inexpensive and high in versatility and that exhibits high catalytic activity has been desired.
As mentioned above, documents for prior art relating to the present invention include Patent document 1: JP-A-8-27136, Patent document 2: JP-A-2003-192679 and Patent document 3: JP-A-2003-192680, and these documents have been incorporated herein by reference.